Mapping Center

Several weeks ago, after a colloquium given by Dr. Aileen Buckley on the devolution of cartographic theory, we approached her about research opportunities that she mentioned. She was glad to accept our help and put us in contact with Dr. A. Jon Kimerling from the Oregon State University. The research he was undertaking during his sabbatical in Redlands, CA dealt with a particular mapping method in the cartographer's bag of tricks - dot density mapping. After discussing the research issues with Dr. Kimerling, we were tasked with developing a series of maps to supplement his research Read More...

Question: What is the difference between filling a polygon with randomly placed dots and creating a dot density map for the polygon?

Filling a polygon with a certain number of randomly placed dots is a form of choropleth mapping where random dots are the area symbol for a quantity that is assumed to be of uniform density throughout the polygon. The choropleth map seen below of San Bernardino county population density uses random dots in this manner. Read More...

Have you ever wondered how you can figure out how far the viewing distance is from the center point of any map?  For example, in my office I have a large map of the world on my wall. It has a scale of 1:9,000,000.  How can you tell the viewing altitude for the map?  This is a very good question that I was asked recently. Read More...

Cynthia Brewer’s new book titled Designed Maps: A Sourcebook for GIS Users is a companion piece designed to compliment the highly successful Designing Better Maps: A Guide for GIS Users published by ESRI Press in 2005. The goal of the book is to offer a graphics-intensive presentation of published maps, providing cartographic details that will prompt GIS users to think about their own maps and how to improve them. Read More...

Not long ago we received a question via Ask a Cartographer that our map projection experts frequently get; it goes something like this:  "When projecting data to WGS84, for example, which transformation is the best to use?"

There are two contexts for this scenario in ArcGIS. The first is as described above, namely, you need to project data and are potentially confronted by a lot of transformation methods and don't know which to choose.  The second context is a bit more complex, which is that you've added data from several sources to your map and you get a somewhat verbose warning (shown at right) that is, if you are like us, all too easy too ignore since it looks complicated. Read More...

Those of you who regularly use the classification dialog will have noticed a new classification method was added in version 9.2. Now available for all data is the geometrical interval classification method which was called "smart quantiles" when it was originally introduced in the ESRI Geostatistical Analyst extension.

This classification method was used for visualizing continuous data and to provide an alternative to the Natural Breaks (Jenks), quantiles, and really any variance minimized (within classes) classification method. The specific benefit of the geometrical intervals classification is Read More...